<!DOCTYPE html>
<html lang="zh">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
        <script src="./scripts/jquery-3.6.1.js"></script>
        <style>
            .box1 {
                float: left;
                width: 100px;
                height: 100px;
                border: 1px red solid;
                margin: 10px;
            }

            .box2{
                float: left;
                width: 200px;
                height: 200px;
                border: 1px orange solid;
            }
        </style>

        <script>
            $(function () {
                $("#btn01").click(function () {
                    // end() 将jQuery对象恢复到筛选前的状态
                    // add() 向jQuery对象中添加元素
                    // contents() 获取当前jQuery对象中所有元素的内容

                    // $(".box1")
                    //     .filter(".a")
                    //     .css("background-color", "#bfa")
                    //     .end()
                    //     .css("border-color", "blue")
                    // $(".box1")
                    //     .css("border-color", "blue")
                    //     .filter(".a")
                    //     .css("background-color", "#bfa")


                    // $(".box1").add(".box2").css("background-color", "#bfa")

                    $(".box1").contents().addBack().css("background-color", "#bfa")
                })
            })
        </script>
    </head>
    <body>
        <button id="btn01">点我</button>

        <hr />

        <div class="box1"><span>我是span</span></div>
        <div class="box1"><span>我是span</span></div>
        <div class="box1"><span>我是span</span></div>
        <div class="box1 a"><span>我是span</span></div>
        <div class="box1 a"><span>我是span</span></div>
        <div class="box1 a"></div>
        <div class="box1"></div>
        <div class="box1 a"></div>
        <div class="box1"></div>
        <div class="box1"></div>

        <div class="box2"></div>
    </body>
</html>
